Juvenile myelomonocytic leukemia (JMML) is a rare clonal myeloproliferative disease in young childhood. Hematopoietic stem cell transplantation (HSCT) is the only way to cure the disease, but relapse after HSCT remains a major cause of treatment failure. A 5-year-old girl with JMML, who had experienced a relapse after the first transplant, did not respond to donor lymphocyte infusion and withdrawal of immune-suppressing agents. She was successfully treated using a second transplant. Detailed reports from the English literature since 1988 relating to a total of 13 JMML patients undergoing a second transplant were reviewed. Seven of the 13 JMML patients (54%) were alive and disease-free, with a median follow-up of 53 months after the second transplant. Within the first 6 months following the initial transplant, 10 JMML patients suffered either autologous recovery (n = 6) or early relapse (n = 4). Seven of the 10 (70%) were alive, with a median survival period of 53 months after the second transplant. Six JMML patients underwent retransplantation within 6 months of the first transplant, with three of these (50%) alive at follow-ups of 24, 57, and 90 months after the second procedure. The authors conclude that a second transplant within 6 months may be worth considering for JMML patients who experience autologous recovery or earlier relapse after the first transplant.